Underreamer



Dec. 24, 1929. w B NlCHOLS 1,740,829-

UNDER BEAMER Filed Jan. 4, 1928.

7 ZIJ f 24 Z Patented Dec. 24, 1929 WILLIAM B. NICHOLS, OF GRAHAM, TEXASUNDERREAMER Application filed January 4, 1928.

This invention relates to improvements in under-reamers and moreparticularly to that type of under-reamers which is employed in drillingoil wells.

One of the objects of the present invention is t provide an under-reamerso constructed that it may be more readily `inserted through the wellpipe, preparatory to operation, than under-reamers of the ordinaryconstruction, and in this connection the invention conten plates somounting the cutters of the underreamer that the same may be retractedand held in retracted vposition while the underreamer is partly insertedinto the Well pipe, and the cutters then released to be automaticallyexpanded to working position,A upon downward movementof the under-reamerin the Well pipe to a position to extend below the lower end of saidpipe.

Another object of the invention is to provide an under-reamer soconstructed that the cutters thereof may be readily removed and othercutters substituted therefor, so that cutters of different sizes may beemployed and 25 therefore the single tool may be adapted to cut boresofdierent diameters, in the oil bearing rock.

Another object of the invention is to provide an under-reamer soconstructed that, on the up stroke of the tool, the cutters will berelieved of strain, at the beginning of said stroke, thus obviating anylikelihood of the cutters being torn loose from the tool.

`While the accompanying drawings and the description which is to follow,constitute a disclosure of the preferred embodiment of the invention, itwill be understood that various changes may be made within the scope ofwhat is claimed.

In the accompanying drawings:

Figure l is a view in side elevation of an under-reamer constructed inaccordance with the present invention;

Figure 2 is a vertical longitudinal sectional view taken substantiallyon the line 22 of Figure 1 looking in the direction indicated by thearrows;

Figure 3 is a bottom plan view of the underremuer;

Figure a is a horizontal sectanal view taken Serial No. 244,461.

substantially on the line 4:4 of Figure 2 looking in the directionindicated by the arrows;

Figure 5 is a perspective view of one of the cutters of theunder-reamer;

Figure 6 is a View similar to Figure 2 illus- 55 trating a means whichmay be employed in retracting the cutters at the time of introducing theunder-reamer into the well pipe.

The under-reamer embodying the invention comprises a cylindrical bodyshell l which is exteriorly ot a diameter nearly equal to the internaldiameter of the well pipe through which the under-reamer is to belowered to working position, and this shell is interiorly threaded nearits upper end as indicated by the numeral 2 and houses a tubular barrelwhich is indicated by the numeral 3 and which is exteriorly threaded fora portion of its length as at 4L to adapt it to be threaded into theshell l. The barrel 8 is provided with a bore indicated by the numeral 5the lower portion of which is of increased diameter as indicated by thenumeral 6, for a purpose to be presently explained, and the barrel isprovided at its lower end, exteriorly, with a circumscribing flange 7which abuts against the lower end of the shell body l and which, for avpurpose to be presently explained, is provided, at intervals in itscircumference, with notches indicated by the numeral 8.

The under-reamer further embodies a plunger including a. stem 9 which isslidably iitted in the bore 5 of the barrel 3 and the lower portion ofwhich is threaded as indicated by the numeral 10 and has adjustablyfitted thereto a nut ll provided in its under face with diametricallyoppositely located notches l2 for the application of a spanner wrenchwhereby the nut may be adjusted upon the stem. A compression spring 13is arranged upon the stem 9 within the enlarged portion 6 of the bore 5of the barrel 3 and bears at its upper end against the shoulder which isprovided at the upper end of the enlargement 6 of the bore and, at itslower end,

vbears against the nut ll, it being understood that the tension of thespring may be varied by adjusting the nut l1 and that the stem 9 mayhave upward sliding movement in the here ef the barrel 3 against thetension of ien the said spring, the spring however normally holding theplunger 9 yieldably in a downwardly shitted position and with the headot the plunger, which is indicated by the numeral 14, abutting against.the upper end of the said barrel 3. rIhe head 14 of the plunger isprovided at its upper end with the Vusual conical threaded stud 15 i'orthe Vconnection of the drill rod of the drilling apparatus, so

that reciprocatory motion. may be imparted to the under-reamer after thesame has been lowered through the Well pipe and past :the lower end ofsaid pipe.

The cutters of the under--reamer are indicatedin general by the numeral16 and each 'compri'sesfaE body 171ha`vingf-a shanlr- 18 projecting fromits'up-perside and Yformed `with Vanl opening19- to accommodateA a pivotpin 2O which is fitted therethrough and chordally throughlthebarrel-3,'near the lower end thereof,-and transversely otfone-oi1 aplurality of slots 21 which-'are provided in the said'. portion of; thebarrel to laccommodate thesaid Shanks-18ct the cutters. The body I17 `ofl-each cutter is ypreferably of segmental Vform anch-whenr` thel cuttersare in the projectedpositionsfshownin Figures 1, 2 and Soi the drawings,the bodies project beyond the outer side of theshell 1 oi' theunderreamer, in position to act upon the rock to be drilled, and inorder that the4 cutters may be rein-iorceduwhen in' this position, theupper l's'ide"ot'each cutterfat opposite sides of the shank 18,*'isfiat-as indicated by the numeral 22 Vandfabuts squarely Vaga-inst thelower end of"the" barrel"{9i-Tand"the` under side of the flange,'7-atsaid end of the barrel, each oi' the cutters? beingforme'd--at its upperend and immediately outwardly of the shank 18, 'wi-th a1K lug-or `boss23 which, in this lposition of the cutter, engages in the respective oneot 'the notches 8. Each cutter 16 is provided, at; the lowerouter sideoii-its body 17, with a cutting lip 2ey having an arcuate, perpendicularouter-'face -25,and ai flat under face y26; these faces defining,`between them, a chipping' edge'?. Atthis point lit will be evident, andparticularly by reference to Figure `6 fof 4the drawings, that the-pivotJ pins. 20 'for the cutters are :freely in-serted in openingsprovided for their reception, inthe barrel 3 lat the opposite sides otthe slotsinsaid barreland that therefore-the pins may bereadily removed,when the-barrel isremoved from the shell" 1. VTherefore cutters ofidiiierent sizesmay -be substituted one for another and the under-reameradapted to undercut holes of various diameters,` and'inthismanner the'invention obviates `the employment ot anumber of' lseparate anddistinct -under-reamers 'for this purpose.

From the foregoing description of the 1invention it will be'evidentthat, when the cutters are -forced inwardly; and-l an upward pull isexertedupon the plunger 9,. the cutting edges of the cutters may bebrought to position within the circumference of the shell 1 andconsequently readily inserted into the well pipe, and, when theunder-reamer has been moved downwardly through the pipe and the lowerend of the under-reamer eX- tends below the lower end of the pipe, thecut-ters willbe automatically proj ected'radially inan. outwarddirection to active position.

,Figure 6 of .the drawings illustrates a convenient meanswhereby thecutters may be Iretracted and temporarily held in such position, priorto insertion of the under-reamer A- intofthe .upper end of. the wellpipe, and in this ligure the numeral 28 indicates hooks which are equalin number to the number of cutters, as for example, three,.andwhich areprovided with overturned, .inwardly projecting bills 29 at their-upper'ends and with eyes 30 `aty their lower ends, the eyesY providingmeans whereby cords. 31.rnay` be connected with the shanlrs of' thehooks to exert a pull upon. the hooks, when their bills are engaged in-soclrets 32 which may vbe formed in the upper endsoi the bosses 23 'ofY.

the cutters. et this point it willbeevident that byV exerting adownward` pull upon all of the cords 31, after the hooks. have beenengaged with the respective cutters, andholding the plunger 9stationary, 'the same being attached -to the rod of the drill, thecutters may be caused to swing vinwardly to the position shown in Figure6,Y and at` this time a cord 33 may bespassed about'the cutters andknotted so as' to retain the cutters in this position, temporarily, thehooks 28,:at this time, beingdisengaged from the cutters. yThe lower endof the under-reamer may then be inserted into the upper end or" the wellpipe until the cutting edges 27, or thefaces 25;k

threaded portion 10, and which portionis' tapered as illustrated in the`drawings and indicated by they numeral 10', will wedge between the inneredges of theshanlrs 18 of the cutters, lwhich edges are, for thispurpose, inclined, and cause outward swinging movement ot the cuttersabout their pivots 20, to activev position, the cutters being in thismanner restrained aga-inst inwarddis- `placemenhon the down-stroke ofthe underreamer, but, on the up stroke, dueto the -momentary yretraction.of the plunger-stem 9, beingpermitted to Yswing inwardly -to clear thesurface of the rock. Y

Having thus described the invention, what lI claim isi 1. Anunder-reamer comprising a barrel,

1a. plunger including a stem slidablyI mounted iso in the barrel, thestem having a threaded portion, a nut threaded onto the said Stein, aspring within the barrel bearing against the said nut and yieldablyholding the Stem in a downwardly shifted position, the stem beingprovided with a head engaging the upper end of the barrel and limitingthe downward movement oi the stem in the barrel, and cutters pivotallysuspended from the lower portion of the barrel, the plunger stein havinga tapered lower end portion for coaction with the inner sides of thecutters, upon downward movement ot the plunger, to Swing the cuttersoutwardly to active position.

2. An under-reamer comprising a barrel, a plunger including a stemslidably mounted in the barrel, cutters, pivotally suspended `from thelower portion of the barrel, the cutters having shoulders engagingagainst the lower end of the barrel, in the outwardly swung position ofthe cutters, the said stem having a tapered lower end portion forcoaction with the inner sides of the cutters, upon downward movement ofthe plunger, to swing the cutters outwardly to active position, a springcoaeting with the plunger and yieldably holding the same in a downwardlyshifted position eoacting with the cutters, the plunger Stem having athreaded portion, and an abutment adj ustably threaded on said portionand engaged by one end of the spring and constituting means whereby thetension of the spring may be varied.

3. An under-reamer comprising a barrel, the said barrel being providedin its lower portion with vertically extending slots opening through itslower end, cutters having shanks pivotally suspended in the upper endsof said slots, the inner Sides of the Shanks being inclined, a shellupon the barrel closing the outer sides of said slots, the outer sidesof the cutter Shanks being engageable against the said shell in theoutwardly swung position of the cutters, the cutters having shouldersengageable beneath the lower end of the barrel in the outwardly swungposition of the cutters, and a plunger including a stem slidably mountedin the barrel and having a tapered lower end portion for coaction withthe said inner sides of the cutter Shanks to eilect outward swinging ofthe cutters to active position upon downward movement of the plunger.

4. An under-reamer comprising a barrel, the said barrel being providedin its lower portion with vertically extending slots opening through itslower end, cutters having shanks pivotally suspended in the upper endsof said slots, the inner sides of the Shanks being inclined, a shellupon the barrel closing the outer sides of said slots, the outer sidesof the cutter Shanks being engageable against the said shell in theoutwardly swung position of the cutters, the cutters having shouldersengageable beneath the lower end of the barrel in the outwardly swungposition of the cutters, and a plunger including a stem Slidably mountedin the barrel and having a tapered lower end portion for coaction withthe said inner sides of the cutter shanks to effect outward swinging ofthe cutters to active position upon downward movement of the plunger,the plunger having a head upon its stem for coaction with the upper endof the barrel in the downward. movement of the plunger.

5. An under-reamer comprising a barrel, the said barrel being providedin its lower portion with vertically extending slots opening through itslower end, cutters having shanks pivotally suspended in the upper endsof said slots, the inner sides of the Shanks being inclined, a shellupon the barrel closing the outer sides of said slots, the outer sidesof the cut-ter shanks being engageable against the said shell in theoutwardly swung position of the cutters, the cutters having shouldersengageable beneath the lower end of the barrel in the outwardly swungposition of the cutters, a plunger including a stem slidably mounted inthe barrel and having tapered lower end portion for coaction with thesaid inner sides of the cutter Shanks to effect outward swinging of thecutters to aotive position upon downward movement of the plungcr, theplunger having a head upon its stem for coaction with the upper end ofthe barrel in the downward movement of the plunger, a portion of thestem of the plunger being threaded, an abutment element adjustablythreaded upon said portion of the Stem, and a compression spring withinthe barrel bearing at its lower end against said abutment element andyieldably holding the plunger in a downward direction.

6. An under-reamer comprising a barrel having slots in its lower endportion, cutters having Shanks disposed within said slots, the walls ofthe slots having openings the outer ends of which open through the outersur- :tace of the plunger, the Shanks of the cutters having openingsregistering with the openings in the walls of the respective Slots,pivot pins removably tted through said openings and removably retainingthe cutter Shanks in the slots, and a plunger including a stem slidablymounted in the barrel and having' a tapered lower end portion forcoaction with the inner sides of the cutter Shanks, in the downwardmovement of the plunger, to effect outward swinging of the cutters toactive position.

In testimony whereof I aiiix my signature.

WILLIAM B. NICHOLS.

